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Year 1: Cardiovascular System > 3. Mechanical Properties of the Heart II > Flashcards

3. Mechanical Properties of the Heart II Flashcards

1
Q

What phases is the heart beat divided into?

A

Diastole and Systole

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2
Q

Define diastole

A

Ventricular relaxation during which the ventricles fill with blood

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3
Q

Define systole

A

Ventricular contraction when the blood is pumped into the arteries

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4
Q

How many sub-phases are in diastole and systole?

A 
Diastole = 4
Systole = 2
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5
Q

What are the 7 events of the cardiac cycle?

A

1) Atrial Systole
2) Isovolumic contraction
3) Rapid ejection
4) Reduced ejection
5) Isovolumic relaxation
6) Rapid ventricular filling
7) Reduced ventricular filling

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6
Q

What type of contraction occurs in diastole?

A

Atrial contraction is part of diastole, since it is also the filling of ventricles

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7
Q

What phase does isovolumetric contraction occur?

A

Systole - you get contraction but there is no change in volume. The pressure builds until it overcomes the pressure of the afterload

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8
Q

What is equation for stroke volume?

A

SV = EDV - ESV

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9
Q

Define ejection fraction?

A

The proportion of the end diastolic volume that is pumped out of the heart. EJ = SV/EDV

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10
Q

What is happening before atrial systole?

A

The blood flows passively through the open AV valves into the ventricles

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11
Q

What does atrial systole achieve?

A

Tops off the blood volume in the ventricles

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12
Q

What is an S4 sound?

A

During atrial systole an abnormal heart sound can be heard which is caused by valve incompetency.

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13
Q

What causes S4?

A

Pulmonary embolism, congestive heart failure and tricuspid incompetence

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14
Q

What is a jugular pulse?

A

A small pulse in the jugular due to atrial contraction causing some blood to go back up the jugular vein

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15
Q

What does the P wave on an ECG stand for?

A

Atrial depolarisation

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16
Q

When does isovolumic contraction occur?

A

Between when the AV valves closing and the semilunar valves opening. During this period the ventricles are completely sealed off.

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17
Q

What does the QRS complex on an ECG stand for?

A

Ventricular depolarisation

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18
Q

What does the first heart sound (S1) signify?

A

The closing of the AV valves

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19
Q

How are the ventricles contracting during isovolumic contraction?

A

Because they are contracting isometrically the muscle fibres are not changing in length but they are generating force and the pressure increases

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20
Q

When does isovolumic contraction end?

A

When the ventricular pressure exceeds the aortic pressure and blood begins to be ejected

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21
Q

What makes the beginning of rapid ejection?

A

Aortic and pulmonary valves opening

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22
Q

What happens to the ventricular volume during rapid ejection?

A

It decreases

23
Q

What causes the c wave in an atrial pressure graph?

A

Caused by the right ventricular contraction causing the tricuspid valve to be pushed into the atrium creating a small wave into the jugular vein

24
Q

What does is shown on an ECG during rapid ejection?

A

No wave

25
Q

What phase marks the end of systole?

A

Reduced ejection

26
Q

What is seen on an ECG during reduced ejection?

A

T wave - cardiac cells begin to repolarise

27
Q

What happens during reduced ejection?

A

Blood leaves the ventricles, ventricular pressure falls, valves begin to close

28
Q

What phase is characterised by the beginning of diastole?

A

Isovolumic relaxation

29
Q

Is there any change in volume during isovolumic relaxation?

A

No

30
Q

What valves are open during isovolumic relaxation?

A

None of them are open

31
Q

What causes the v wave on an atrial pressure graph?

A

Blood pushing against the tricuspid valve, giving a second jugular pulse

32
Q

What is the dichrotic notch?

A

A small, sharp increase in aortic pressure due to the rebound pressure against the aortic valve as the distended aortic wall relaxes

33
Q

What does the second heart sound (S2) signify?

A

When the aortic and pulmonary valves close

34
Q

What occurs during rapid ventricular filling?

A

AV valves open again resulting in the passive filling of the ventricles

35
Q

What is S3?

A

A third heart sound that is abnormal; signifies turbulent ventricular filling

36
Q

What is the slow filling of ventricles called?

A

Reduced ventricular filling = Diastasis

37
Q

What are the differences and similarities between the cardiac cycle of the left and right side of the heart?

A

Right = lower pressures

Same volume of blood ejected

38
Q

What is the systemic blood pressure value?

A

120/80 mmHg

39
Q

What is the pulmonary blood pressure value?

A

25/5 mmHg

40
Q

What is the PAWP?

A

Pulmonary Artery Wedge Pressure

41
Q

Describe a pressure-volume loop

A

See diagram

42
Q

Where on the pressure-volume loop is the preload?

A

Point 1, which is the end diastolic volume

43
Q

Where on the pressure volume loop is the afterload?

A

Just after point 2, this is when the left ventricle encounters the aortic pressure when the aortic valve begins to open

44
Q

How can the Frank-Starling relationship be applied to hypertension?

A

High BP = increased afterload = increased pressure to open aortic valve + less shortening so stroke volume decreases

45
Q

Cardiac output =

A

CO = Stroke volume x Heart rate

46
Q

What is stroke volume affected by?

A

Preload
Afterload
Contractility

47
Q

Define contractility

A

Contractile capability of the heart

48
Q

What is a measure of contractility?

A

Ejection fraction

49
Q

How can you increase contractility?

A

Sympathetic stimulation - adrenaline

50
Q

How does an increase in contractility affect the Frank-Starling relationship in terms of a pressure-volume loop?

A

It shift point 3 to the left, there is an increase in stroke volume as more blood is pumped out

51
Q

What changes occur during exercise?

A

Contractility is increased due to increased sympathetic activity. End diastolic volume increases due changes in the peripheral circulation

52
Q

Give examples of changes in peripheral circulation

A

Vasoconstriction and muscle pump. They both increase venous return to the heart

53
Q

What is the EF of a healthy individual?

A

65%

54
Q

What can the EF of a patient with heart failure drop down to?

A

35%

Year 1: Cardiovascular System (21 decks)

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